Does rumination mediate the relationship between mindfulness and depressive relapse?

OBJECTIVES: Major depressive disorder is a significant mental illness that is highly likely to recur, particularly after three or more previous episodes. Increased mindfulness and decreased rumination have both been associated with decreased depressive relapse. The aim of this study was to investigate whether rumination mediates the relationship between mindfulness and depressive relapse. DESIGN: This prospective design involved a secondary data analysis for identifying causal mechanisms using mediation analysis. METHODS: This study was embedded in a pragmatic randomized controlled trial of mindfulness-based cognitive therapy (MBCT) in which 203 participants (165 females, 38 males; mean age: 48 years), with a history of at least three previous episodes of depression, completed measures of mindfulness, rumination, and depressive relapse over a 2-year follow-up period. Specific components of mindfulness and rumination, being nonjudging and brooding, respectively, were also explored. RESULTS: While higher mindfulness scores predicted reductions in rumination and depressive relapse, the relationship between mindfulness and relapse was not found to be mediated by rumination, although there appeared to be a trend. CONCLUSIONS: Our results strengthen the argument that mindfulness may be important in preventing relapse but that rumination is not a significant mediator of its effects. The study was adequately powered to detect medium mediation effects, but it is possible that smaller effects were present but not detected. PRACTITIONER POINTS: Mindfulness may be one of several components of MBCT contributing to prevention of depressive relapse. Although the original rationale for MBCT rested largely on a model of relapse causally linked to rumination, our findings suggest that the mechanism by which mindfulness impacts relapse is more complex than a simple effect on rumination.